JPH0685620U - rice cooker - Google Patents

Abstract

(57) [Summary] [Purpose] A rice cooker is manufactured at low cost by eliminating the heat-retaining heater. [Constitution] The inner pot 2 is housed in the outer container 5 of the rice cooker body 1. Either the outer container 5 or the inner pot 2 is made of a magnetic material. A primary coil 7 is arranged on the shoulder 6 of the outer container 5. Oscillator 8 in primary coil 7
2 provided on the lid 3 by applying high frequency current from the
An induced electromotive current is generated in the secondary coil 22, and the lid heating means 2
While heating the inner lid 21 provided on the lid body 3 by 4,
The inner pot 2 is induction-heated and kept warm.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a rice cooker, and more particularly to a rice cooker capable of keeping an inner pot warm.

[0002]

[Prior art]

 Conventionally, in a rice cooker, an inner pot is housed in an outer container of the rice cooker body, and the inner pot is indirectly heated by a heater provided on the bottom surface of the outer container, or recently, an electromagnetic induction action by a heating coil. By direct heating (in this case, the inner pot must be made of a magnetic material such as stainless steel) to heat and cook the rice. When the cooking of rice is completed, the heating heater or heating coil is de-energized, and the heat-retaining heater provided on the upper outer periphery of the outer container is energized to heat the outer container to keep the inner pot warm. I am trying to do it. In addition, the inner lid of the lid that closes the inner pot energizes the primary coil provided on the shoulder of the rice cooker body, and the induced electromotive force is generated in the secondary coil provided on the lid by electromagnetic induction. It is heated by removing the dew adhered to the lid by heating it with a heater for heating the lid.

[0003]

[Problems to be solved by the device]

 However, in the rice cooker, since a warming heater is required to keep the inner pot warm, the number of parts is increased and the manufacturing man-hours for mounting the rice cooker are increased, resulting in cost increase. Also, since the heating state of the inner lid is determined by the amount of electricity supplied to the primary coil, the inner lid may be overheated in some cases, such as yellowing of rice and melting of the resin portion of the lid. There is a fear of occurrence. The present invention has been made in view of the above problems, and an object of the present invention is to provide a rice cooker which can be manufactured at a low cost without a heat-retaining heater and in which the inner lid is not overheated.

[0004]

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention accommodates an inner pot in an outer container of a rice cooker main body and arranges a primary coil on a shoulder portion of the outer container, By supplying a high frequency current from the oscillator to the primary coil, an induced electromotive current is generated in the secondary coil provided on the lid, and the lid heating means heats the inner lid provided on the lid. In the rice cooker configured as described above, the outer container or the inner pot is made of a magnetic material, and the primary coil is arranged near the upper outer peripheral portion of the inner pot so that the inner lid is formed by the primary coil. In addition to the above heating, the outer container or inner pot is induction-heated to indirectly or directly keep the inner pot warm. Further, temperature detecting means may be provided in the vicinity of the switching transistor of the oscillator, and the output from the oscillator may be suppressed when the temperature detected by the temperature detecting means exceeds a predetermined temperature.

[0005]

[Action]

 According to the above configuration, when a high frequency current is applied to the primary coil by the oscillator, an induced electromotive current is generated in the secondary coil. As a result, the inner lid is heated by the lid heating means and the dew attached to the inner lid is removed, while the outer pot or inner pot is induction-heated and the inner pot is kept warm. If a temperature detecting means is provided in the vicinity of the switching transistor of the oscillator, there is a fixed relationship between the detected temperature and the heating temperature of the inner lid. Judging from the detected temperature, heating of the inner lid is stopped by stopping the energization of the primary coil.

[0006]

【Example】

 Next, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a rice cooker, which is roughly composed of a rice cooker body 1, an inner pot 2 and a lid 3. The rice cooker main body 1 includes a rectangular exterior body 4 and an outer container 5 housed in the exterior body 4. A primary coil 7 is disposed on the shoulder portion 6 of the outer casing 4 near the upper outer peripheral portion of the inner pot 2. The outer container 5 is made of a magnetic material such as stainless steel, and a heater (not shown), an oscillator 8 for the primary coil 7, and a control for controlling the oscillator 8 are provided on the outer surface of the bottom of the outer container 5. A circuit 9 and a temperature sensor 10 such as a thermistor are provided.

As shown in FIG. 3, the oscillator 8 includes a rectifier circuit 12 connected to an AC power source composed of four diodes 11 connected in a bridge, and a resonance capacitor 13 connected to the rectifier circuit 12. And a switching transistor 14 connected in series with the capacitor 13, and a drive pulse oscillating circuit 15 for outputting a transistor driving pulse to the base of the switching transistor 14. The temperature sensor 10 is arranged in the vicinity of the switching transistor 14, and the detected temperature is input to the control circuit 9 described above. The primary coil 7 is connected in parallel with the capacitor 13 of the oscillator 8 to form an LC resonance circuit.

The inner pot 2 is made of metal and is housed in the outer container 5 of the rice cooker body 1. The lid 3 includes an outer lid 16, a lid ring 18 integrated with the outer lid 16 by a welding ring 17, a heat radiating plate 19 made of stainless steel fixed to the central portion of the lid ring 18, and the heat radiating plate 19 An inner lid 21 detachably attached to a protrusion 20 formed in the central portion of the rice cooker, and is rotatably provided on a shoulder portion 6 of the rice cooker body 1 about a hinge portion (not shown). .

At the outer peripheral portion of the space formed by the outer lid 16 and the lid ring 18 of the lid body 3 (slightly inside the welding ring 17), the secondary side is provided so as to face the primary side coil 7. A coil 22 is housed, and a lid heating coil 24 connected to the secondary coil 22 via an impedance conversion circuit 23 is housed in the central portion. A packing 25 is sandwiched between the lid ring 18 and the outer peripheral portion of the heat radiating plate 19 so that the inner pot 2 can be closed in a sealed state.

In the rice cooker having the above-mentioned configuration, after the rice is cooked by the heater (not shown), the primary coil 7 keeps the heat and the inner lid 21 is exposed. That is, after the rice is cooked, the drive signal is issued from the control circuit 9 to the drive pulse oscillation circuit 15 of the oscillator 8. As a result, the drive pulse oscillation circuit 15 outputs a drive pulse to the base of the transistor 14 to turn on the transistor 14, energize the primary coil 7 for a predetermined time, and then turn off the transistor 14.

As a result, a high-frequency current flows in the primary coil 7 to generate an alternating magnetic field, the outer container 5 located in this magnetic field is induction-heated, and an induced electromotive current flows in the secondary-side coil 22. . The induced electromotive current generated in the secondary coil 22 causes a high-frequency current to flow in the lid heating coil 24 via the impedance conversion circuit 23, thereby generating an alternating magnetic field. As a result, the heat dissipation plate 19 is induction-heated, the temperature of the inner lid 21 rises, and the dew attached to the inner lid 21 is removed. In this way, the primary coil 7 can be used not only for exposing the inner lid 21 but also for keeping the temperature of the inner pot 2. Therefore, the warming heater conventionally arranged on the upper outer peripheral portion of the outer container for keeping heat. Is unnecessary and the number of parts can be reduced to reduce the cost.

By the way, the temperature near the transistor 14 is detected by the temperature sensor 10 during the heat retention and the exposure. Since this detected temperature has a constant relationship with the heating temperature by the inner lid 21, if the temperature (abnormal temperature T ₁ ) corresponding to the state where the inner lid 21 is abnormally heated is detected, the control circuit 9 causes the oscillator. A control signal is issued to the drive pulse oscillation circuit 15 of No. 8 to keep the transistor 14 in the off state. As a result, the high-frequency current flowing through the primary coil 7 is stopped, and the induction heating of the radiator plate by the lid heating coil 24 is suppressed. As a result, the temperature of the inner lid 21 decreases.

If the detected temperature falls below the temperature T ₂ (see FIG. 5) in which the abnormal temperature T ₁ has hysteresis (see FIG. 5), the control circuit 9 drives the oscillator 8 to generate a drive pulse oscillation circuit 15 A drive signal is issued to the primary coil 7, and a high-frequency current is applied to the primary coil 7 in the same manner as described above to perform heat retention and dew exposure.

In the above-described embodiment, the outer coil 5 is heated by the primary coil 7 to keep it warm when the temperature is kept warm. However, the inner pot 2 is made of a magnetic material so that the inner pot 2 can be directly heated. You may make it heat and heat. In the above embodiment, the primary coil 7 is energized or cut off depending on whether the temperature detected by the temperature sensor 10 exceeds the abnormal temperature. However, the primary coil 7 is energized in a stepwise or continuous manner depending on the detected temperature. The amount may be controlled. Further, in the above-described embodiment, the heat radiation plate 19 is induction-heated by the lid heating coil 24 to prevent the dew from adhering to the inner lid 21, but as shown in FIG. Alternatively, the heater 26 may directly heat the heat dissipation plate 19. In this case, the impedance conversion circuit 23 is unnecessary, and the heat dissipation plate 19 need not be made of stainless steel.

[0015]

[Effect of device]

 As is apparent from the above description, according to the rice cooker of the present invention, the outer pot or the inner pot is made of a magnetic material, and the inner pot can be kept warm by induction heating with the primary coil. Unlike the conventional method, a heat insulation heater is not required, making it easier to manufacture and reducing costs.

Further, since the temperature detecting means is provided in the vicinity of the switching transistor of the oscillator and the amount of electricity supplied to the primary side coil is controlled according to the detected temperature, the inner lid can be appropriately heated. No yellowing of rice or melting of resin part of the lid will occur.

[Brief description of drawings]

FIG. 1 is a perspective view of a rice cooker according to an embodiment.

FIG. 2 is a partially enlarged sectional view of FIG.

FIG. 3 is a partial electric circuit diagram of FIG.

FIG. 4 is a partially enlarged cross-sectional view showing another embodiment.

FIG. 5 is a hysteresis characteristic diagram at an abnormal temperature.

[Explanation of symbols]

1 ... Rice cooker body, 2 ... Inner pot, 3 ... Lid body, 5 ... Outer container, 6
... shoulder, 7 ... primary coil, 8 ... oscillator, 21 ... inner lid,
22 ... Secondary side coil, 24 ... Lid heating coil (lid heating means).

Claims (2)

[Scope of utility model registration request] 1. An inner pan is housed in an outer container of the rice cooker main body, a primary coil is arranged on a shoulder portion of the outer container, and a high-frequency current is supplied from an oscillator to the primary coil.
In a rice cooker in which an induced electromotive force is generated in a secondary coil provided on a lid to heat an inner lid provided on the lid by a lid heating means, the outer container or the inner pot is made of a magnetic material. On the other hand, by arranging the primary side coil near the upper outer peripheral portion of the inner pot, while heating the inner lid with the primary side coil, induction heating of the outer container or inner pot is performed indirectly or directly. A rice cooker characterized by keeping the inner pot warm. 2. A temperature detecting means is provided in the vicinity of the switching transistor of the oscillator, and when the temperature detected by the temperature detecting means exceeds a predetermined temperature, the output from the oscillator is suppressed. The rice cooker according to Item 1.